A washing machine is a domestic appliance for cleaning clothes, linens, and other laundry. A washing machine may include a tub and a drum positioned in the tub that is sized to receive laundry for cleaning. The washing machine may include an electric motor that causes the drum to rotate relative to the tub during a washing operation. In some washing machines, the electric motor may be connected to the drum via a transmission system including, for example, belts and pulleys. The electric motor may also be connected to the drum via a drive shaft. Washing machines including the latter type of electric motor are often referred to as “direct drive” washing machines.
Electric motors typically include a stator and a rotor configured to rotate relative to the stator. The stator may be fixed to the tub of the washing machine and may include a number of stator field coils. The rotor may include one or more magnets that interact with the stator coils.
During operation, the stator coils may be sequentially energized with electricity to create an electromagnetic field that rotates the rotor. The electromagnetic field generates tangential magnetic forces that act on the stator and may cause the stator to vibrate and create undesired acoustic noise.